Slurry flow in a valveless hydrothermal reactor and its application to hydrothermal decomposition of bamboo powder

A valveless hydrothermal reactor was developed to investigate the flowability and reaction behavior of bamboo powder slurry. A multi-stage model with 160 stages, each approximated as a horizontal tube, was proposed to predict slurry flow and reactor performance, using empirical formulas for pressure drop. This model captures the axial variation of bamboo powder during hydrothermal treatment. The treatment significantly altered bamboo composition and properties. Hemicellulose content decreased from 22.4% to 4.18%, and the reduction of the 1731 cm −1 peak indicated preferential hemicellulose decomposition. The number of molecules required to completely cover the sorption sites ( q m ) decreased from 0.0441 to 0.0336 g-water/g-dry solids, and the wettability indicator ( d c cosθ ) decreased from 23.7 to 15.5 nm, reflecting improved hygroscopicity, wettability, and dimensional stability of the hydrothermal products. Further investigation of xanthan gum decomposition, added as a dispersant, is needed to refine the model's predictive accuracy. Overall, this study demonstrates that hydrothermal treatment effectively modifies both structural and surface properties of bamboo powder, providing insights for optimizing biomass processing and improving product performance. • Flowability of bamboo slurry studied in a valveless hydrothermal reactor. • Multistage model predicts slurry behavior considering reactor tube changes. • Hydrothermal treatment reduced hygroscopicity and water absorption. • Bamboo powder underwent hydrothermal treatment, improving dimensional stability.